When a naked, mentally ill white man with an AR-15 killed four young adults of colour at a nearby Waffle House, Nashville-based doctor and gun policy scholar Jonathan M. Metzl once again advocated for common-sense gun reform. But as he peeled back evidence surrounding the racially charged mass shooting, a shocking question emerged: Did the approach he championed have it all wrong?

Long a leading expert at the forefront of a movement advocating for gun reform as a matter of public health, Dr Metzl has been on constant media call in the aftermath of fatal shootings. But the 2018 Nashville killings led him on a path toward recognising the limitations of biomedical frameworks for fully diagnosing or treating the impassioned complexities of American gun politics. Increasingly, as Dr Metzl came to understand it, public health is a harder sell in a nation that fundamentally disagrees about what it means to be safe, healthy or free. This brilliant, piercing analysis shows mass shootings as a symptom of our most unresolved national conflicts. What We've Become ultimately sets us on the path of alliance-forging, racial-reckoning and political power-brokering we must take to put things right.

Jonathan M. Metzl is the Frederick B. Rentschler II professor of sociology and psychiatry and the director of the Department of Medicine, Health, and Society at Vanderbilt University. The award-winning author of Dying of Whiteness: How the Politics of Racial Resentment Is Killing America's Heartland and other books, he hails from Kansas City, Missouri, and lives in Nashville, Tennessee.